Cam lobes on a camshaft can be roughed or finished to the desired contour by grinding or milling. As shown in my co-pending U.S. patent application Ser. No. 07/377,067, filed July 10, 1989, the roughing or finishing of such cams may be carried out by abrasive belts. The belts are guided along variable paths according to the cam contours desired. Specifically, each belt is guided by a shoe which engages the backside of the belt at its point of contact with the cam periphery. Each shoe is mounted on one end of an actuator which is moved by a power unit. The power unit is CNC controlled to move the actuator back and forth, and hence cause the shoe to move the abrasive belt toward and away from the camshaft axis. In order to accurately grind the cam lobes, it is desirable to continuously track or monitor the angular position of the camshaft during its rotation so that this information can be input to the CNC controlled power unit for its proper operation.
In the past, the monitoring of the angular position of the workpiece has been carried out by mechanism including a pick-up member adapted to engage a locating pin on the workpiece. Locating pins vary in diameter from camshaft to camshaft, and accordingly the pick-up member usually has an enlarged hole or recess for receiving the pin. This has the advantage of making it possible for the pick-up member to accommodate pins of varying diameter. However, the disadvantage is that the pick-up member can only imprecisely follow the rotation of the workpiece, resulting in inaccurate feed back to the CNC control.
One object of this invention is to provide an improved pick-up member adapted to closely follow the rotation of the workpiece despite variations in pin size, and accordingly feed back to the CNC control the exact rotative position of the workpiece at all times, consistently and accurately.
In accordance with a specific embodiment about to be described, the pick-up member has a locating pad and yieldable, resilient means in spaced, opposed relation to the locating pad for clamping the pin on the workpiece against the locating pad.
More particularly, the resilient, yieldable means comprises a leaf spring one end of which is secured to the pick-up member and the free end of which opposes the locating pad.
These and other objects and features of the invention will become more apparent as the following description proceeds, especially when considered with the accompanying drawings.